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• 皮安输入偏置电流电磁计放大器：ADA4530

**AD\Test\2026\September\MeasureHighResistorADA4530.SchDoc ***

01【ADA4530测量高阻】

一、测量电阻

刚才测试了平安输入偏置电流放大器ADA4530的基本特性， 特别是通过电容充电方法测量了它在。 保护地的情况下，它的输入端口的偏置电流大概是在20飞安左右， 那下面我们利用这个运放来测量一下一个大阻值的电阻特性， 这为将来评价一些插座的绝缘特性，积累数据经验， 测量原理也很简单，它本质上就是将aDa4530作为高阻抗电压变换器， 利用待测电阻上的电流， 给一个电容充电。 电容充电的上述速率可以反映出电流的大小， 进而可以计算出待测电阻的大小。 铺设单面PCB， 适合一分钟制板。 一分钟之后得到测试电路板。 。

二、测量结果

选择一个标称值为3G欧姆的电阻，焊接在待测电路板上 选择一个电容。 它的标称值为0.1微法， 下面我们通过记录 aDa4530输出电压变换速率， 反映了充电电容上的电压变化率， 这样我们可以得到对应的充电电流大小。 在电路板上我们通过可调电阻将待测电阻一端设置为0.487伏。 那么在3G欧姆上会流过162P安的电流， 在0.1微法的充电电容上， 每隔一秒大概变化1.62毫伏， 我们连续测量20个数据点， 大概花费了22秒，可以看到充电电流是比较恒定的， 反映在输出电压，几乎是随着时间线性变化， 根据测量时间。 以及电压变化， 我们可以计算出充入电容的电流大概是153.7P安， 与前面根据标称值计算出来的162P安是接近的。

接下来我们更换另外一个红色的高阻值电阻， 它上面没有标准值，估计是在早期购买的时候留下的高阻值电阻， 使用普通的绝缘电阻表测量它的电阻， 已经超过了电阻表的最高量程二十几欧姆， 下面我们使用上述电容充电方法测量它的电阻大小， 将它的一端充电电压提高到4.0伏， 测量100个数据点，耗时120秒左右， 根据时间和电压的变化， 以及充电电容的容值， 可以计算出充电电流大概是41.9P安。 由此可以推断出，刚才红色的电阻， 它的阻值是100G欧姆。

※总结 ※

本文测试了利用ADA4530 飞安级输入电流运放来测量高阻值电阻的过程 利用电容充电的方法， 可以准确的测量高达100G电阻的阻值， 但是这个过程由于需要测量充电电容电压的变化， 所以测量时间比较长。 那下面我们利用aDa4530组成反向运放放大器， 直接用来测量输入电阻， 查看一下测量的精度如何。

fromheadmimport*fromtsmodule.tsvisaimport*dm3068open()vdim=[]tdim=[]startt=time.time()foriinrange(100):v=dm3068vdc()t=time.time()-startt vdim.append(v)tdim.append(t)time.sleep(1.0)printff(i,v,t)tspsave("measure",vdim=vdim,tdim=tdim)C=0.1e-6dt=tdim[-1]-tdim[0]dv=vdim[-1]-vdim[0]Ioffset=dv*C/dt printff(dt,dv,Ioffset)plt.plot(tdim,vdim,lw=3)plt.xlabel("Time(s)",color="steelblue",fontsize=24)plt.ylabel("Vout(V)",color="steelblue",fontsize=24)plt.grid(True,which='both',linestyle='--',alpha=0.7)plt.tight_layout()plt.show()

vdim=[0.0820,0.0825,0.0830,0.0835,0.0841,0.0846,0.0851,0.0856,0.0861,0.0866,0.0871,0.0876,0.0881,0.0886,0.0892,0.0897,0.0902,0.0907,0.0912,0.0917,0.0922,0.0927,0.0932,0.0937,0.0942,0.0948,0.0953,0.0958,0.0963,0.0968,0.0973,0.0978,0.0983,0.0988,0.0993,0.0998,0.1003,0.1008,0.1014,0.1019,0.1024,0.1029,0.1034,0.1039,0.1044,0.1049,0.1054,0.1059,0.1064,0.1069,0.1074,0.1079,0.1084,0.1089,0.1095,0.1100,0.1105,0.1110,0.1115,0.1120,0.1125,0.1130,0.1135,0.1140,0.1145,0.1150,0.1155,0.1160,0.1165,0.1170,0.1175,0.1180,0.1185,0.1191,0.1196,0.1201,0.1206,0.1211,0.1216,0.1221,0.1226,0.1231,0.1236,0.1241,0.1246,0.1251,0.1256,0.1261,0.1266,0.1271,0.1276,0.1281,0.1286,0.1291,0.1296,0.1301,0.1306,0.1311,0.1316,0.1321]tdim=[0.1916,1.4018,2.6107,3.8230,4.9994,6.2386,7.4493,8.6587,9.8661,11.0562,12.2861,13.4976,14.7061,15.9138,17.1236,18.3353,19.5415,20.7237,21.9606,23.1708,24.3808,25.5906,26.7728,28.0103,29.2174,30.4267,31.6365,32.8163,34.0557,35.2655,36.4440,37.6842,38.8932,40.1133,41.3108,42.4984,43.7294,44.9396,46.1494,47.3585,48.5464,49.7766,50.9865,52.1977,53.4054,54.6141,55.8240,57.0441,58.2177,59.4528,60.6710,61.8729,63.0795,64.2686,65.4997,66.7100,67.9177,69.1284,70.3119,71.5479,72.7549,73.9340,75.1740,76.3852,77.5928,78.8030,79.9807,81.2219,82.4317,83.6401,84.8487,86.0363,87.2675,88.4766,89.6655,90.8963,92.1047,93.3155,94.5236,95.7144,96.9439,98.1522,99.3607,100.5717,101.7594,102.9901,104.1994,105.4087,106.6189,107.7977,109.0365,110.2473,111.4267,112.6643,113.8755,115.0837,116.2929,117.4737,118.7119,119.9226]

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